The colouration is extremely strange
Blue sharp lines didn't just appear-- you did something to make them appear.  But, they were probably always there.  Probably, because you imported this mesh using a function that marked edges containing custom, per-face normals as sharp edges.
The solution?  If you were happy with your normals before you cleared sharp edges, but not after?  Roll back to just before you cleared sharp edges.  Or else, remark those edges as sharp, if you remember which edges they were.